Introduction to the function of additives in metalworking fluids
September 02, 2022
Metal processing oil or liquid is mainly used for metal processing, which plays the role of lubricating and cooling, and also has the functions of rust prevention and cleaning. General metal processing oil includes cutting fluid, cutting oil, emulsion, stamping oil, quenching agent, high temperature oil, extreme pressure cutting fluid, grinding fluid, anti-rust oil, cleaning agent, blackening agent, deep drawing oil, etc. Metalworking cutting fluid is a low-foaming, high-lubricity soluble liquid, which can minimize maintenance costs even in environments with high requirements for machining fluids, and is basically applicable to all types of metals and alloys. It is very effective for general machining of most ferrous metals, especially when machining mild steel, cast iron, stainless steel and other special steels, it can play an excellent lubricating and cooling effect at the same time. Today, I will introduce several commonly used metalworking fluid additives.
1. Sodium Nitrite Sodium nitrite is white crystal, light yellow after absorbing moisture, easily soluble in water, cheap, good rust resistance, can not be used alone, often used together with sodium carbonate to make the solution slightly alkaline (pH=9~ 10). In the processing fluid, the dosage of sodium nitrite is about 0.25%. It has good anti-rust properties and is effective for rust prevention of steel, but cannot be used for copper and its alloys. It is irritating to the skin of individuals, do not enter or splash into the eyes when using. 2. Anhydrous Sodium Carbonate Anhydrous sodium carbonate is white powder, soluble in water, and its aqueous solution is alkaline. Generally used together with sodium nitrite or other anti-rust additives. In the working fluid composed of sodium nitrite, it can promote the anti-rust effect of sodium nitrite on steel. Its usual dosage of 0.3% to 0.6% can be used to soften hard water and neutralize free acid in processing fluid. 3. Trisodium Phosphate Trisodium phosphate is a colorless or white crystal, soluble in water, insoluble in alcohol, and weakly alkaline; it can be used to soften hard water; it can be used as a cleaning agent and rust inhibitor in aqueous processing fluids. 4. Triethanolamine Triethanolamine is a colorless or light yellow viscous liquid, easily miscible with water and strongly alkaline. It is often used together with sodium nitrite; it can react quickly to form salts when it encounters weak acids; it can absorb carbon dioxide in the air and does not volatilize with water vapor. After it acts with hydrochloric acid, it can be used as an emulsifier to prepare emulsions and aqueous processing fluids. It is only suitable for steel and cannot be used for non-ferrous metals alone. 5. Benzotriazole Benzotriazole is white or light yellow loose needle-like crystals, easily soluble in alcohols, slightly soluble in oil and water, used together with co-solvents such as alcohols, lipids or sodium petroleum sulfonate, etc. Solubility in oil is particularly effective in preventing discoloration of copper due to the chemical interaction of benzotriazole with copper. Its general dosage is about 0.1%. 6. Barium Petroleum Sulfonate Barium petroleum sulfonate is a yellowish or brown-red viscose, which can be dissolved in oil and grease under heating and stirring. It is a by-product of the production of white oil or white petrolatum, with abundant supply, low price, good anti-rust performance, and strong replacement ability for human sweat. , aluminum, copper and other metal materials rust prevention. 7. Sodium Petroleum Sulfonate Sodium petroleum sulfonate is a brown-red oily liquid or viscous colloid. It is soluble in oil. It is an emulsifier with good anti-rust properties. The anti-rust effect is not good, so it needs to be used in combination with other anti-rust additives.
8. Oxidized petroleum grease and its barium soap Oxidized petroleum grease and its barium soap are brown-black waxy substances. Oxidized petroleum grease barium soap has better anti-rust effect than oxidized petroleum grease. It is suitable for anti-rust of steel, copper, aluminum and other metal materials. For cast iron and brass It also has good anti-rust properties. 9. Zinc Naphthenate Zinc naphthenate is a brown-black viscous colloid, often used in combination with barium petroleum sulfonate, and has good anti-rust properties for steel, copper, aluminum and other metal materials. 10. Aluminum Stearate Aluminum stearate is a white powder that dissolves in oil under heating and stirring conditions. 11. Sorbitan Monooleate Sorbitan monooleate, also known as Siben-80, is a greasy viscous liquid, easily soluble in water, and is a non-ionic surfactant. Its cleaning effect is good. It is often used in combination with barium petroleum sulfonate to enhance the anti-rust effect. 12. Diacid Diacid is colorless flake crystal, slightly soluble in water, easily soluble in ethanol and ether. It is obtained by separation of castor oil after heating saponification and thermal cracking. 13. Ethanol Ethanol, commonly known as alcohol, is a colorless, transparent, volatile and flammable liquid with the smell of wine and a pungent pungent taste. It is soluble in water, methanol, ether and chloroform, and is an excellent solvent. 14. Dimethicone Dimethicone is a colorless transparent liquid, insoluble in heavy oil and water, soluble in light oil. Due to the high viscosity of dimethyl silicone oil and the small amount of addition, it should be diluted with kerosene (kerosene: dimethyl silicone oil is 9:1) before use, and then the working fluid is vigorously stirred to dilute the diluted dimethyl silicone oil. The silicone oil is distributed as evenly as possible in the machining fluid. The amount added is a few ten thousandths.
